Portable navigation devices (PNDs) that include GPS (Global Positioning System) signal reception and processing functionality are well known, and are widely employed as in-car or other vehicle navigation systems.
In general terms, a modern PND comprises a processor, memory (at least one of volatile and non-volatile, and commonly both), and map data stored within said memory. The processor and memory cooperate to provide an execution environment in which a software operating system may be established, and additionally it is commonplace for one or more additional software programs to be provided to enable the functionality of the PND to be controlled, and to provide various other functions.
Typically these devices further comprise one or more input interfaces that allow a user to interact with and control the device, and one or more output interfaces by means of which information may be relayed to the user. Illustrative examples of output interfaces include a visual display and a speaker for audible output. Illustrative examples of input interfaces include one or more physical buttons to control on/off operation or other features of the device (which buttons need not necessarily be on the device itself but could be on a steering wheel if the device is built into a vehicle), and a microphone for detecting user speech. In a particularly preferred arrangement the output interface display may be configured as a touch sensitive display (by means of a touch sensitive overlay or otherwise) to additionally provide an input interface by means of which a user can operate the device by touch.
Devices of this type will also often include one or more physical connector interfaces by means of which power, and optionally data signals, can be transmitted to and received from the device, and optionally one or more wireless transmitters/receivers to allow communication over cellular telecommunications and other signal and data networks, for example Wi-Fi, Wi-Max GSM and the like.
PND devices of this type also include a GPS antenna by means of which satellite-broadcast signals, including location data, can be received and subsequently processed to determine a current location of the device.
The PND device may also include electronic gyroscopes and accelerometers which produce signals that can be processed to determine the current angular and linear acceleration, and in turn, and in conjunction with location information derived from the GPS signal, velocity and relative displacement of the device and thus the vehicle in which it is mounted. Typically such features are most commonly provided in in-vehicle navigation systems, but may also be provided in PND devices if it is expedient to do so.
The utility of such PNDs is manifested primarily in their ability to determine a route between a first location (typically a start or current location) and a second location (typically a destination). These locations can be input by a user of the device, by any of a wide variety of different methods, for example by postcode, street name and house number, previously stored “well known” destinations (such as famous locations, municipal locations (such as sports grounds or swimming baths or other points of interest), and favourite or recently visited destinations.
Typically, the PND is enabled by software for computing a “best” or “optimum” route between the start and destination address locations from the map data. A “best” or “optimum” route is determined on the basis of predetermined criteria and need not necessarily be the fastest or shortest route. The selection of the route along which to guide the driver can be very sophisticated, and the selected route may take into account historical, existing and/or predicted traffic and road information.
In addition, the device may continually monitor road and traffic conditions, and offer to or choose to change the route over which the remainder of the journey is to be made due to changed conditions. Real time traffic monitoring systems, based on various technologies (e.g. mobile phone data exchanges, fixed cameras, GPS fleet tracking) are being used to identify traffic delays and to feed the information into notification systems.
PNDs of this type may typically be mounted on the dashboard or windscreen of a vehicle, but may also be formed as part of an on-board computer of the vehicle radio or indeed as part of the control system of the vehicle itself. The navigation device may also be part of a hand-held system, such as a PDA (Portable Digital Assistant) a media player, a mobile phone or the like, and in these cases, the normal functionality of the hand-held system is extended by means of the installation of software on the device to perform both route calculation and navigation along a calculated route.
Route planning and navigation functionality may also be provided by a desktop or mobile computing resource running appropriate software. For example, an on-line route planning and navigation facility is provided at routes.tomtom.com, which facility allows a user to enter a start point and a destination, whereupon the server to which the user's PC is connected calculates a route (aspects of which may be user specified), generates a map, and generates a set of exhaustive navigation instructions for guiding the user from the selected start point to the selected destination. The facility also provides for pseudo three-dimensional rendering of a calculated route, and route preview functionality which simulates a user travelling along the route and thereby provides the user with a preview of the calculated route.
In the context of a PND, once a route has been calculated, the user interacts with the navigation device to select the desired calculated route, optionally from a list of proposed routes. Optionally, the user may intervene in, or guide, the route selection process, for example by specifying that certain routes, roads, locations or criteria are to be avoided or are mandatory for a particular journey. The route calculation aspect of the PND forms one primary function, and navigation along such a route is another primary function.
During navigation along a calculated route, it is usual for such PNDs to provide visual and/or audible instructions to guide the user along a chosen route to the end of that route, i.e. the desired destination. It is also usual for PNDs to display map information on-screen during the navigation, such information regularly being updated on-screen so that the map information displayed is representative of the current location of the device, and thus of the user or user's vehicle if the device is being used for in-vehicle navigation.
An icon displayed on-screen typically denotes the current device location, and is centred with the map information of the current road and surrounding roads in the vicinity of the current device location and other map features also being displayed. Additionally, navigation information may be displayed, optionally in a status bar above, below or to one side of the displayed map information, examples of navigation information include a distance to the next deviation from the current road required to be taken by the user, the nature of that deviation possibly being represented by a further icon suggestive of the particular type of deviation, for example a left or right turn. The navigation function also determines the content, duration and timing of audible instructions by means of which the user can be guided along the route. As can be appreciated a simple instruction such as “turn left in 100 m” requires significant processing and analysis. As previously mentioned, user interaction with the device may be by a touch screen, or additionally or alternately by steering column mounted remote control, by voice activation or by any other suitable method.
A further important function provided by the device is automatic route re-calculation in the event that: a user deviates from the previously calculated route during navigation (either by accident or intentionally); real-time traffic conditions dictate that an alternative route would be more expedient and the device is suitably enabled to recognize such conditions automatically, or if a user actively causes the device to perform route re-calculation for any reason.
Although the route calculation and navigation functions are fundamental to the overall utility of PNDs, it is possible to use the device purely for information display, or “free-driving”, in which only map information relevant to the current device location is displayed, and in which no route has been calculated and no navigation is currently being performed by the device. Such a mode of operation is often applicable when the user already knows the route along which it is desired to travel and does not require navigation assistance.
Devices of the type described above provide a reliable means for enabling users to navigate from one position to another.
When navigating along a route, or planning a route, users may be presented with alternative routes between an origin and destination by a navigation device, or other system having route generating functionality. Rather than simply providing the user with a single route optimised with respect to time, distance or another criterion such as fuel economy, this provides the user with the opportunity to decide which of a number of possible routes they prefer for some reason. These routes would typically not be optimised with respect to the given criterion, e.g. time, but might be preferable to a user for another reason, e.g. in that they avoid a particular junction or stretch of road that the user dislikes, are more scenic, etc.
Generating and selecting alternative routes which are sensible routes a user might wish to use presents some challenges. It will be appreciated that numerous routes could theoretically be provided which differ in some respect from a first, e.g. fastest, route. In particular, in order to provide more useful alternative routes that are more likely to be helpful to a user, it is desirable for the alternative routes to differ to an appropriate degree from the first, e.g. fastest, route.
Some prior art techniques for generating an alternative to a main route between an origin and a destination have involved blocking off a central portion of the main route, such that the segments forming this part of the route may not be considered in a route planning process for generating the alternative route. However, preventing overlap between significant portions of the main and alternative routes in this way may force alternative routes to deviate significantly from the main route, and include inappropriate detours. An example of one such set of alternative routes is shown in FIG. 6.
Certain techniques have been proposed to try to ensure that the alternative routes generated are sensible, i.e. user friendly alternatives, e.g. by consideration of the degree of permissible overlap, etc. Some such techniques have been developed as part of a project funded by the European Commission entitled “eCO-friendly urban Multi-modal route PlAnning Services for mobile uSers”, or eCOMPASS, and are described, for example, under section 5 of the document entitled “FP7—Information and communication technologies: Grant Agreement No. 288094: D2.3.2—Validation and empirical assessment of algorithms for eco-friendly vehicle routing: Workpackage WP2—Algorithms for Vehicle Routing” available at http://www.ecompass-project.eu/sites/default/files/eCOMPASS-Deliverable-D2.3.2-v1.4.pdf. Further descriptions of the techniques for generating alternative routes can be found in the document entitled “Improved Alternative Route Planning” by Andreas Paraskevopoulos and Christos Zaroliagis, ATMOS 2013—13th Workshop on Algorithmic Approaches for Transportation Modelling, Optimization, and Systems, 10.4230/OASIcs.ATMOS.2013.108 available at http://drops.daqstuhl.de/opus/volltexte/2013/4248/pdf/10.pdf. The content of both these applications is incorporated herein by reference. In these techniques, rather than simply blocking a middle portion of a route when generating an alternative route thereto, a network of overlapping alternative routes is provided between an origin and destination, whose segments may join one another or split from one another, etc. An example of one such set of routes is shown in FIG. 7.
The Applicant has realised that there remains a need for improved methods and systems for providing a user with alternative route options during travel. The present invention, in some aspects, may provide methods and systems for generating alternative routes. In accordance with some further aspects, the present invention may provide methods and systems for determining routes taken by a user through a navigable network where alternative route options exist. In accordance with further aspects, the present invention may provide more efficient and improved methods for providing alternative route options to a user.